1. Field of the Invention
The present invention relates to a gas supply apparatus and method, and more particularly, to a gas supply apparatus and method capable of efficiently supplying a liquefied gas filled into a gas container in a stable state by vaporizing the liquefied gas within the gas container.
2. Background Art
Gas such as WF6, CIF3, BCl3 and SiH2Cl2 used in the field of semiconductor production and so forth are filled and stored in gas containers in a liquid state at normal temperature (liquefied gas state), and when these gases are used, the gas container is heated from the outside as necessary to promote vaporization of the liquefied gas within the gas container.
In addition, in the supplying of such gases, although it is necessary to maintain the pressure of supplied gas led out from the gas container at a roughly constant pressure close to a set pressure, in the past, the pressure inside the gas container or the pressure of a gas supply line connected to it was measured, and the amount of heating of the gas container was regulated based on that change in pressure. However, in the case of controlling the pressure using only this type of pressure feedback, due to the low responsiveness, there are times when it becomes difficult to attain stable control in cases of large fluctuations in the amount of gas supplied, and, in particular, during the initial supply of gas when the pressure inside the gas container is low, there was the problem of a long period of time being required until the pressure stabilized. Moreover, in the case of supplying gas from a gas container, it is also necessary to reliably determine the time when the gas container is to be replaced by detecting the residual amount of gas in the gas container.
The object of the present invention is to provide a gas supply apparatus and method, which together with being able to efficiently heat or cool a gas container from the outside, is able to maintain the pressure of supplied gas roughly constant, while also being able to reliably detect the residual amount of gas in the gas container.
The gas supply apparatus of the present invention supplies a gas by vaporizing a liquefied gas filled in a gas container. This apparatus comprises an installation stand having an upper surface on which the gas container is placed; at least one nozzle which discharges a heating medium towards a bottom surface of the gas container and is provided in a hole formed in the installation stand; and a heating medium discharge path which discharges the heating medium from a space between the bottom surface of the gas container and the upper surface of the installation stand.
According to the gas supply apparatus, since liquefied gas filled into a gas container can be supplied by evaporating and vaporizing the liquefied gas efficiently, and the supply pressure can be stabilized, gas supply can be carried out in a stable state.
The heating medium discharge path may be at least one through hole provided in the installation stand.
The heating medium discharge path may be formed by surface irregularities provided in the upper surface of the installation stand.
The gas supply apparatus may further comprise a cylindrical cover that covers the periphery of the gas container, and the heating medium discharge path may be formed so that heating medium discharged from the nozzle flows into a gap between the gas container and the cylindrical cover.
The installation stand may be supported by a weighing device capable of measuring changes in the weight of the gas container, and the nozzle may be provided in a non-contact state with respect to the installation stand.
The gas supply apparatus may further comprise a pressure measuring device which measures the pressure of gas supplied from the gas container; a flow rate measuring device which measures the flow rate of the gas; and a temperature regulating device which regulates the temperature of the heating medium based on measured values of the pressure measuring device and the flow rate measuring device.
The gas supply method of the present invention comprises supplying a vaporized gas while heating or cooling a gas container into which liquefied gas has been filled by a heating medium; measuring the pressure and flow rate of the vaporized gas flowing out from the gas container; regulating the temperature of the heating medium based on the difference between the measured flow rate of the vaporized gas and a reference flow rate when the measured flow rate is outside an allowed range of flow rate fluctuation predetermined with respect to a reference flow rate, and regulating the temperature of the heating medium based on the difference between the measured pressure and a reference pressure when the measured flow rate is within the allowed range of flow rate fluctuation relative to the reference flow rate.
Another aspect of the gas supply method comprises supplying a vaporized gas while heating or cooling a gas container into which liquefied gas has been filled by a heating medium; measuring the pressure and flow rate of the vaporized gas flowing out from the gas container; regulating the temperature of the heating medium based on the difference between the measured flow rate and a reference flow rate when the measured pressure is lower than a lower limit pressure predetermined with respect to a reference pressure, and regulating the temperature of the beating medium based on the difference between the measured pressure and a reference pressure when the measured pressure is equal to or greater than the lower limit pressure.